I think the given here is that you will have a booth to paint your car and parts in so here are my thoughts on the matter. Standard air circulating fans have electrical current running through them and even if there is no spark they can produce a static charge that will ignite a volatile vapor. The fans that are normally used in paint booths, have blades that are aluminum so that no spark will be created if they strike the side of the shroud. Also they are powered by an electric motor from outside the booth. The drive pulley of the motor protrudes into a pipe large enough for the fan belt. Usually the fan belt is 2 or 3 feet long and drives a pulley, on a shaft. That shaft goes out of the tube where it is connected to the fan blade. Perhaps your local major paint rep (PPG ?) knows a source for good used proper fans. Many of us have taken the chance and not had any problem. I personally have and got away with it. One must consider that the inside of a paint booth full of ignitable vapors could become a fire box. My understanding is that the booth would not explode but rather have a hot flame that radiates around the entire booth, like a cloud on fire. Minimizing the risk would be to have a massive air flow to minimize the ignitable vapors in the air. Most booths have a fire retardant system in them and it would not be very costly for you to put one in your booth. Just requires hooking up to a good water supply, plumbing the ceiling with copper tubing and installing 2 or 3 temperature sensitive shower heads (the kind they use in all commercial buildings). Even though you are in a booth with some air flow you must wear a fresh air respirator or you will suffer brain and nervous system damage. In the paint industry the saying is, if you can smell it it is hurting you. And today some very toxic and poisonous chemicals have no smell at all.